In a common tube-incorporated tire, when the tube is wounded by stabbing with a nail or the like, air within the tube is liable to be leaked from the stabbed wound through a small gap between the tire and the tube and through a nipple bore in a rim to the outside, leading to a so-called punctured state.
Therefore, there is conventionally known a tire tube having a suitable amount of a liquid sealant previously filled therein to automatically and temporarily repair a stabbed wound produced upon stabbing of the tube (see Japanese Patent Application Laid-open No. 58-74342). This tire tube is formed by previously incorporating a capsule filled with a sealant within the tube at the time of molding the tube, and breaking the capsule after molding of the tube to charge the sealant into the tube. For this reason, when an external force is applied to the capsule to break the capsule, the tube is liable to be damaged and moreover the sealant may clog an air valve of the tube, and or clog a pressure gauge when the pressure of the air in the tube is measured, in some cases.
To avoid this, it is conceived that the inside of the tube is divided by a partition wall into an air chamber filled with air and a sealant chamber filled with a sealant, so that the sealant can be filled directly into the sealant chamber without use of a capsule.
At a step of vulcanizing the sealant-incorporated tire tube having such a construction, a tube blank is placed into a heating die, and heated air or water vapor of a high temperature is supplied through the air valve into the air chamber, thereby bringing the peripheral walls of the air chamber and the sealant chamber into close contact with the heating die and bringing the partition wall into close contact with the peripheral wall of the sealant chamber. In this state, the heating die is heated to perform the vulcanization. In this case, if the air remains within the sealant chamber in the tube blank placed in the heating die, even if the heated air or the water vapor of the high temperature is supplied into the air chamber, the partition wall may not be brought into close contact with the peripheral wall of the sealant chamber, resulting in a possibility that the tube blank may only unevenly be heated.
In addition, if the vulcanization is carried out in a state in which the air remains within the sealant chamber, when the tube blank is removed from the heating die, the air encapsulated and thermally expanded in the sealant chamber, forces the partition wall to be expanded toward the peripheral wall of the air chamber, and thus, an expanding tendency or bias is provided to the partition wall. If the expanding tendency or bias is provided to the partition wall in this manner, when the peripheral wall of the sealant chamber and the partition wall are wounded by stabbing with a nail or the like, the partition wall is spread toward the peripheral wall of the air chamber, thereby providing a possibility that the air within the air chamber may flow into the sealant chamber to reduce the effect of the sealant.